Railways invented the time
Before trains, every town kept its own clock, set by the sun. Noon in Bristol arrived about ten minutes after noon in London, and nobody minded, because nothing travelled fast enough for it to matter. Then came the RAILWAY, and a timetable that said a train left at ten was suddenly meaningless if ten meant something different at each STATION down the line.
The Great Western Railway solved it in 1840 by running everything on London time, and other companies followed. Stations hung clocks showing 'railway time', and in 1880 Parliament finally made one time official across Britain. The clock on your wall is set the way it is because of trains.
Why the tracks are that far apart
Most of the world's TRACKS sit exactly 4 feet 8½ inches apart, an oddly specific number inherited from the horse-drawn wagonways of northern England, where George Stephenson had worked before he built railways.
Not everyone agreed. Isambard Kingdom Brunel built the Great Western at just over 7 feet, which gave a faster, steadier ride — and lost anyway, because where two gauges met, everything and everyone had to change trains. Parliament settled on the narrower one, and in 1892 the last broad-gauge line was converted in a single weekend by thousands of men working along the track with crowbars. On the Friday the trains ran on Brunel's gauge; by Monday they ran on Stephenson's.
Steel on steel
A train wheel touches the rail over an area roughly the size of a small coin. That tiny, hard contact patch is the whole point: steel rolling on steel wastes very little energy, so one LOCOMOTIVE can drag thousands of tonnes of FREIGHT with far less fuel per tonne than any lorry.
The same lack of friction is why a train needs a mile or more to stop, and why drivers obey a SIGNAL set long before the danger. There is one more piece of quiet cleverness: train wheels are not flat but slightly coned, and joined by a solid axle. Drifting to one side puts the wider part of one wheel on the rail and the narrower part of the other, which nudges the whole thing back to the middle. A train steers itself round gentle curves without anything being steered.
One train to a block
Because trains cannot stop quickly or swerve, railway safety works by keeping them apart. The line is divided into sections called blocks, and the rule is simple: only one train in a block at a time. A SIGNAL at the entrance tells the driver whether the section ahead is clear, and early railways passed that information along the line by telegraph, by hand.
The modern version is beautifully simple. A small electric current runs along the rails of each block; the steel axles of a train short it out, and the missing current is what tells the system a train is there. If anything fails — a broken wire, a power cut — the signal shows danger by default, because the safest assumption is that the line is occupied.
The fast ones
Japan opened the first high-speed line in 1964, and the Shinkansen still measures its average delay in seconds rather than minutes. Modern high-speed trains cruise beyond 300 kilometres an hour on dedicated track, and maglev test trains, which float on magnets and never touch a rail at all, have passed 600.
Everything else in the grid is still doing its job underneath all that. A JUNCTION lets one line become two, the SUBWAY and the TRAM move cities that would seize up without them, and the WHISTLE means the same thing it always did.